This invention relates to cartridge loaders which access tape from data storage tape cartridges, for example, for data storage drives, and, more particularly, to accessing tape having a leader pin to unwind the tape from the data storage tape cartridge.
Data storage tape cartridges provide convenient and low cost means for storing data. As one example, portable data storage tape cartridges may be carried from a data storage drive of one data processing system to a data storage drive of another data processing system. As another example, large quantities of data storage tape cartridges may be boxed and stored in archival storage areas, such as salt mines, and, if needed subsequently, retrieved and shipped to the user, for example, for data recovery.
A data storage tape cartridge may comprise a tape leader pin, which is at one end of the tape, and is positioned at an opening in the cartridge. A cartridge loader, for example, of a data storage drive, will have a leader block that engages an aligned tape leader pin to unwind the tape from the data storage tape cartridge.
On occasion, handling of the cartridges allows one or more cartridges to be dropped. In such cases, the impact may displace one or both ends of a tape leader pin, such that the tape leader pin is misaligned. Typically, the ends of the tape leader pin are positioned in slots in opposite sides of the cartridge, and, when misaligned, the cartridge expands slightly such that one or both ends of the tape leader pin falls out of the slot. With one end of the tape leader pin misaligned by being out of the slot, the misaligned end may be pulled in a direction into the cartridge by the tape to which it is attached, or may be moved sideways. With both ends of the tape leader pin out of their slots, the entire tape leader pin may be pulled into the cartridge by the tape to which it is attached, and be absent from the cartridge opening.
A missed attempt by the cartridge loader to engage its leader block with the tape leader pin of a cartridge, and to unwind the tape from the cartridge and attempt to thread the tape leader pin and tape without being aware of the actual position of the tape leader pin, may result in damage to, or failure of the cartridge loader, or of the data storage drive or other device with its cartridge loader, requiring replacement.
Optical detectors, cartridge loaders, methods and computer program products are provided in accordance with aspects of the present invention for detecting alignment and/or absence of a tape leader pin in an opening of a tape cartridge. The tape leader pin has at least one exposed cylindrical surface, for example, top and bottom exposed cylindrical surfaces.
In accordance with one aspect of the present invention, at least one light source scans at least one portion of the opening of the tape cartridge, as the cartridge is moved with respect to the light source.
At least one optical detector detects reflections of the light source from the opening of the tape cartridge and provides at least one detected reflection waveform signal of the detected reflections.
In one embodiment, detection logic receives the detected reflection waveform signal(s), and analyzes the detected reflection waveform signal(s) for deviation from a cylindrical surface reflection of the tape leader pin, if any; and determines, from the analyzed deviation of the at least one detected reflection waveform signal, if any, tilt angle misalignment of the at least one exposed cylindrical surface, if any. The tilt angle misalignment of the cylindrical surface may indicate that the tape leader pin is misaligned.
As one example, the deviation from a cylindrical surface reflection of the detected waveform signal comprises a broader waveform signal representing an elliptical surface reflection if the tilt angle is substantially in the direction of scan, and comprises a narrower and lower amplitude waveform signal representing a conical surface reflection if the tilt angle is substantially perpendicular to the direction of scan.
In another embodiment for detecting absence of a tape leader pin in the opening of a tape cartridge, the detection logic analyzes the detected reflection waveform signal for deviation of amplitude from the cylindrical surface reflection of the tape leader pin, if any; and determines, from the analyzed amplitude deviation of the detected reflection waveform signal, if any, absence of an exposed cylindrical surface at the portion of the opening of the tape cartridge, if any. A low amplitude likely indicates the lack of a reflection from the tape leader pin, in turn indicating that at least the end of the tape leader pin being examined is likely to have been pulled into the cartridge.
In a further embodiment, where the tape leader pin has cylindrical surfaces at each end and is normally vertically positioned in the opening, at least one light source is focussed on and scans top and bottom portions of the opening of the tape cartridge as the cartridge is moved. At least one optical detector is focussed on the top and bottom portions of the opening to separately detect reflections of the light source from the top and bottom portions of the opening and provides detected reflection waveform signals of the detected reflections. Detection logic analyzes the detected reflection waveform signals, respectively from the top and bottom portions of the opening, comparing the detected reflection waveform signals for difference in displacement and for difference in amplitude of cylindrical surface reflections of the top and bottom exposed cylindrical surfaces of the tape leader pin, if any; and determines, from the analyzed differences of the detected reflection waveform signals, if any, tilt angle misalignment of the tape leader pin, if any. For example, if the top and bottom cylindrical surfaces are displaced, the tape leader pin is likely to be tilted in the direction of scan; and, if there is a difference in amplitude, one end or the other is likely to have been pulled into the cartridge.
In a still further embodiment, the light source(s) are stationary, and a cartridge loader moves the data storage tape cartridge such that the opening of the tape cartridge is moved past the light source(s); and a loading sensor provides a signal indicating that the data storage tape cartridge is being loaded. The detection logic is responsive to the loading sensor signal to operate the light source(s) a predetermined time subsequent to the loading sensor signal, such that the light source(s) are operated as the opening of the tape cartridge is moved past the light source(s) by the loader. The detection logic analyzes the detected reflection waveform signals for misalignment and/or for absence of the tape leader pin.